After a surface dirt layer was removed, a mixture of solvents were used to slowly remove the varnish layer. Additional residues of an older varnish layer were discovered in Lady Hamilton’s costume, which made her dress appear brown, rather than the original purple-blue colour. These residues were also removed.

A photograph taken during cleaning demonstrates the large visual colour shift achieved by the varnish removal, revealing the bright colours the artist intended for the composition. Additionally the depth in the portrait was reintroduced, and smaller details in the painting were finally visible."

The pdf (which is here) also includes an analysis of Le Brun's original processes in crafting the composition, shifting the anatomy, extending the canvas.